Engineer s or surveyor s instrument



(No Model.)

0. L. BERGER. ENGINEERS OR SURVEYORS INSTRUMENT. No. 591,153. Patented001;. 5, 1897.

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Nl'lED STATES {PATENT OFFICE.

CHRISTIAN L. BERGER, OF BOSTON, MASSACHUSETTS.

ENGINEERS OR SURVE YORS INSTRUMENT.

SPECIFICATION formingpart of Letters Patent'No. 591,153, dated October5, 1897. Application filed December 17,1896. Serial-No. 616,003. onmodel.)

To aZZ whom it may concern:

Be it known that I, CHRISTIAN L. BERGER, of Boston, county of Suffolk,State of Massachusetts, have invented an Improvement in Engineers orSurveyors Instruments, of which the following description,in connectionwith the accompanying drawings, is a specification, like letters on thedrawings designating like parts.

In engineers and surveyors instruments, particularly in those of veryhigh grade, capable of or intended for use in astronomical work, it isoften desirable to employ different arrangements or figures ofcross-wires, and in order to do this it has been necessary heretoforeeither to provide a complicated arrange ment of reticule-frames or toremove one reti, cule-frame and insert another one when a change incross-wires was desired.

One object of my invention is to provide a telescope or instrumenthaving the required plurality of cross-wire figures mounted therein andinstantly adjustable for separate use as desired without any chance forconfusion or mistake or necessity for any removal or substitution.

A further object of my invention relates to the provision of novelreticules or cross-wire figures particularly adapted to this class ofWork and obviating recognized objections to the usual arrangement ofcross and stadia Wires, as will be hereinafter explained. I combine withthe usual bisecting or quartering cross wires or lines additional sunwires or lines for solar Work, arranging the latter ments used for thissolar Work, &c., require washed off and gathers as sediment on theglassand the bubble is changed when not desired. .I have therefore invented alevel of superior sensitiveness, made homogeneous and integralthroughout, and which cannot accumulate any sediment, and have alsoprovided an improved connection or passage between the chamber and themain tube.

The details of my invention will be fully pointed out in the followingdescription, reference being had to the accompanying drawings, theinvention being more particularly defined in the appended claims.

In the drawings, Figure 1 shows in perspective a sufficient portion of atransit provided with my improvements to furnish a clear understandingthereof. Fig. 2 is a vertical cross-section of the telescope-tube, takenon line 2, Fig. 1, showing my improved reticule, its frame, andadjustments. Fig. '3 is a vertical section taken on line 3 3, Fig. 2.

i Fig. 4' is an enlarged view in elevation, showing the usualarrangement of cross-wires, the position of the suns disk beingindicated therein by dotted lines. Fig. 5 is a greatlyenlarged viewsimilar to Fig. 4, showing one form of my improvement in the arrangementof the cross wires or lines. Figs. 6 and 7 are similar views of anotherform thereof, the latter view showing the position of the suns disk.Fig. 8 is a vertical longitudinal section of the spirit-level, theinclosing casing thereof being removed. Figs. 9 and 10 areverticalcross-sectional views of the air-chamber, the main tube of thelevel being represented in end elevation, showing different means ofcommunication between the chamber and the tube.

The telescope A, containing a focusing-eyepiece a, object-glass, andfocusing-screw a therefor, mounted on a horizontal axis B in a frame 0,is of any usual or preferred kind.

D designates the reticule-frame, customarily provided to hold thecross-wires, which may be platinum wires, spider-webs, lined glass, orother reticule, and delicately mounted for accurate adjustment in thetelescopetube by means of capstan-screws d. In-this frame D, I havemounted a plurality of reticules or sets of cross wires, one behindanother, two sets being shown, the frame being milled out slightly onits inner. circumference, as at cl, to receive one set d behind thefront set d For convenience of illustration I have shown the front setof wires as being the same in figure or arrangement, as shown enlargedin Fig. 6, the rear set of wires being the simple X figure as used intunnel-work. However, I wish it to be understood that any figuresdesired may be employed. The successive reticules are in parallel planesso closely adjacent to each other that either one may be quickly broughtinto accurate focus by means of the focusing-eyepiece a, turning thelatter forward slightly serving to make the wires d visible and thewires (1 invisible or out of focus and moving the eyepiece outwardslightly having the reverse effect.

another reticule, such as shown in Fig. 4 or in Fig. 6, were behind it,the two reticules being carried by separate frames and independent ad jlisting-screws, it will be evident that as one reticule would be shiftedthe wires of the other reticule would very nearly but not quite overlieits wires, making it exceedingly difficult, excepting to the mostskilled operator, to determine which reticule should be shifted andwhich adj Listing-screws to operate, the result being that probably theoperator would find it impossible or at least very tedious to correctlyadjust the reticules.

I will now describe the new reticules shown in Figs. 5 to 7.

By reference to Fig. 4:, where the position of the sun is indicated by adotted circle, it will be easy to understand the uncertainty laboredunder by the engineer in bisectin g or quartering the sun, as it iscalled. As the operator looks through the telescope all is absolutelydark excepting a very small bright disk, (Fig. 2 showing the actualdimensions l of the reticule,) this bright spot being the sun, as seenthrough the telescope. Now it is evident that it is very difficult todetermine whether this spot or disk is accurately bisected or not by thelines of spider-web fineness arranged as usual, Fig. 4, a slight errorto right or left being imperceptible to the eye. Accordingly I haveinvented the arrangements of lines or wires, as shown in Figs. 5, 6, and7, the former having the suns disk indicated by a dotted circle and thelatter by a white space. The horizontal and vertical sightingcross-wires are indicated at e e and the stadia-wires at e. Arranged atsuch distances from the center as to cut off segments of the suns diskare horizontal and vertical sun-wires e in Fig. 5 and oblique sun-wirese in Figs. 6 and 7.

Supposing it were found that the suns It will be evident that by myinvention it will be no longer possible to make the error abovealludedto in bisecting the sun, for the reason that the foursmallsegments must all be seen by the operator before he can read hismeridian, and these cannot be seen until the sun is exactly centeredorbisected, as will be more apparent from Fig. 7, remembering that allthe lines out of the field of the suns disk are invisible to theoperator, as indicated by the shading.

The advantage of arranging the sun-wires obliquely or at an angle offorty-five degrees, as shown at e 12 is that even the most carelessoperator cannot, in his regular engineering-work, mistake them for thestadia-wires e or for the sighting-wires 6, but on the contrary they actas pointers, as it were, to direct the operator to the proper center ofthe reticule.

, Another marked advantage of the inclined square arrangement, asshownin Figs. 6 and 7, is that it gives additional accuracy andquickness of adjustment in placing the wires by affording a geometricaltest or a proof or demonstration by geometrical figure that the wiresareproperly placed, for it will be readily understood by those skilledin the art without going into unnecessary details here that the lines 06 must intersect the sighting cross-wires e at common points, and thatthe upper and lower of these points will fall just outside of thestadia-lines 6', so that if in sighting the sun the operator should findthat no segments of the suns disk were cut off by the sun-wires or thatthe segments were large he would know at once that the lines underobservation were wrong or by inspection of the geometrical figure thatthe suns lines were not correctly placed. In other words, the inclinedsquare of Fig. 6 serves as a check or means of correction by whichaccuracy is insured, besides affording the convenience similarly withthe reticule of Fig. 5 of combining in one reticule and one telescopeall the wires required both for solar and for general work.

As before briefly explained, when an instrument of the characteremployed for purposes of illustration in Fig. 1 is used for the highgrade of work which we have been discussing the usual spirit-level isineffective.

The usual spirit-level of the best kind comprises a tube, as F, and achamber, as G, the latter being cemented onto the former by isinglass orother cement, a segmental opening being provided between the two, asindicated by dotted lines in Fig. 10. The manufacture of these levels isvery expensive and very delicate, and a most serious objection hasarisen in their use by reason of the fact that the agitation and perhapsthe chemical action of the contained liquid has resulted indisintegrating the cement, the latter appearing as a mass of dark specksin the tube F; also, the said agitation has caused the transfer of theliquid between the tube and chamber too freely and at times when it wasnot desired,

5 that a small bubble in the summer-time would therebyimpairin g theefficiency of the instrument until the proper proportions were re-.stored, so as to accommodate the bubble to the temperature. I haveobviated these objections as follows: Having ground and finished thetube F (the latter being ground and on a curvature preferably of aradiusof three hundred to five hundred feet) and filled it with thefluid, a quick-acting fluid, such as sulfuric ether, being used, the endpiece g .is placed snugly over the end of the tube under suchtemperature and conditions as to produce a vacuum therein in use, andthe edges of the end piece 9 are then fused directly onto the tube F, soas to constitute therewith one integral solid piece without any foreignmat ter to be ground away by the impact of the fluid. This impact ismarked in field instruments. It is to be understood that the chamber isprovided to permit the use of a quickacting fluid, as mentioned, as witha slow fluid, such as alcohol, the bubble is so slow to settle that itmakes the process of leveling too tedious; but a quick-acting fluid,like ether, has a coefficient of expansion so marked become in wintertemperature as long as the tube and render the level useless. Thereforethe chamber G is provided in order to permit the length of bubble to beadjusted as the temperature changes. Ihave found that the improperinterchange of fluid already alluded -to between the tube F and chamberG is obviated by providing a vertical slit, asg, extending. radially, asshown in Fig. 9, or for some uses a more restricted slit or aperture maybe used at or near the center, as at g Fig. 10. Preferably, also, thereis a depres sion g in the glass adjacent the slit or opening g,cooperating therewith in retarding the passage of the bubble or air fromone side to the other in case the level is turned bottom side up.

' By the provisions of my invention, as herein described, it is renderedpossible to use a transit or level telescope without change for all thedelicate purposes mentioned, whereas heretofore a telescope orattachments had to be specially provided to reach the same ends.

While I. have described the details of my invention in connection withan ordinary e11 gineers and surveyors transit, it is to be understoodthat this is illustrative merely, inasmuch as my improvements hereindescribed are in no wise restricted to any instrument and instruments,but may be used in various relations and instruments; nor do I restrictmyself to the various details herein set forth, inasmuch asmany changesin form,

arrangements, and proportions of parts may be resorted to within thespirit and scope of my invention.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is

1. In a telescope, the combination with the object-glass, andafocusing-eyepiece, of a reticule-f rame, a plurality of reticulestherein, in parallel planes, and means to simultaneously adjust all ofsaid reticules in and with relation to the telescope, substantially asdescribed.

2. In a reticule, the combination with the sightingwires, andstadia-wires, of sun-wires arranged to intercept segments of the sunsdisk, substantially as described.

3. In a reticule, the combination with the sighting-wires, of sun-wiresarranged obliquely to said sighting-wires to intercept segments of thesuns disk, substantially as described.

i. In a reticule, the combination with the sighting-wires, of sun-wiresarranged in an inclined square intersecting said sightingwires at itscorners,substantiallyas described.

5. A spirit-level, having. a main tube and an air-chamber separatedtherefrom by the apertured end of the main tube, made in one integral,homogeneous piece, substantially as described.

6. A spirit-level, comprising a main tube,

and an air-chamber, said chamber being sep arated from the tube by awall, and the latter being provided witha narrow opening 'at or near thecenter thereof, substantially as described.

7. A spirit-level, comprisinga main tube, and an air-chamber, saidchamber being separated from the tube by a wall and. the latter beingprovided with a narrow opening at or near the center thereof, andextending radially outward therefrom, substantially as described.

8. A spirit-level, comprising a main tube, and an air-chamber, saidchamber being separated from the tube by a wall, and the latter beingprovided with a narrow opening at or near the center thereof, andextending radially outward therefrom, the inner connecting,- surface ofthe said tube and chamber adjacent the outer end of the said openingbeing depressed, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

CHRISTIAN L. BERGER.

Witnesses:

GEO. I-I, MAXWELL, JOHN C. EDWARDS.

